Using organic molecules in a memory cell reduces the size of the memory cell because the size of the organic molecules themselves is small. Consequently, the memory density can be increased. Therefore, it has been attempted to interpose, between upper and lower electrodes, molecules having the capability of being changed in resistance by the presence or absence of an electric field or the injection of charges, and thereby to make a memory cell. The molecules changes the resistance by a voltage applied across the upper and lower electrodes. By utilizing the change of resistance, the memory cell stores a data. And, by detecting a difference in flowing currents, a data stored in the memory cell can be read. It is important in an organic molecular memory to reduce characteristics variations between a plurality of memory cells in realizing an organic molecular memory with high operational stability.